In electronic devices such as personal computers in recent years, following the increase in operation processing amount and speed, there are mounted heat generating components that generate heat by themselves with high power consumption. As a typical example of the heat generating components, there is a CPU as an electronic component mounted in an electronic device. The amounts of heat generated from those many electronic devices have gone on increasing. Normally, various electronic components used in the electronic devices are limited in their use temperature range in terms of their heat-resistance reliability or the temperature dependence of their operating characteristics.
Therefore, with respect to these electronic devices, it is of urgent necessity to establish a technique for efficiently discharging to the outside the heat generated by the heat generating components inside the electronic devices.
Generally, in an electronic device such as a personal computer, a metal heat sink, a heat pipe, or the like as a heat absorbing component is attached to a heat generating component to carry out thermal diffusion to the entire electronic device by heat conduction.
Further, in an electronic device, an electromagnetic cooling fan is attached to a housing of the electronic device to dissipate heat from the inside to the outside of the electronic device.
However, for example, in an electronic device such as a notebook personal computer in which electronic components are mounted at high density, a heat dissipation space is small inside the electronic device.
Therefore, with the conventional cooling system using a cooling fan alone or the combination of a cooling fan and a heat pipe, there has been a cooling effect adaptable to a CPU with a power consumption up to about 30 W, but it has been difficult to sufficiently dissipate heat inside a CPU with a higher power consumption.
Even if the heat dissipation is enabled, it is essential to dispose a cooling fan with high blast performance and, in the case of such an electromagnetic cooling fan, sound calmness has been largely marred due to noise such as wind-cutting sounds of rotating blades thereof.
Further, also with respect to personal computers for use as servers, there has been an increasing demand for miniaturization and more sound calmness following the increase in diffusion rate thereof and thus there has arisen a problem of heat dissipation similar to that in notebook personal computers.
In view of this, for efficiently dissipating increased heat to the outside, there has been studied a cooling apparatus of the liquid-cooling type in which a cooling medium is circulated.
For example, Japanese Unexamined Patent Application Publication (JP-A) No. 2003-67087 as conventional art 1 discloses a portable information processing device liquid-cooling system in which, at the bottom of a personal computer body portion having a heat receiving head for receiving heat generated from a heat generating component in the personal computer body portion, there is disposed a liquid-cooling portion housing provided with a connecting head to which the heat from the heat generating component is transferred through the heat receiving head, a tube connected to the connecting head and filled with a cooling medium, and a pump for circulating the cooling medium.
Japanese Unexamined Patent Application Publication (JP-A) No. 2004-84958 as conventional art 2 discloses an electronic device, a liquid-cooling system, and a liquid-cooling tank, having a liquid-cooling structure for circulating a cooling liquid to thereby cool a high-heat component with the cooling liquid and further having a gas incorporation preventing structure for preventing the incorporation of air into a power source.
In the electronic device, the liquid-cooling system, and the liquid-cooling tank, a first heat dissipation pipe is a heat dissipation pipe on the inflow end side where the cooling liquid flows into the cooling tank and a second heat dissipation pipe is a heat dissipation pipe on the outflow end side where the cooling liquid flows out of the cooling tank. The cooling liquid flows into the tank from the first heat dissipation pipe and flows out into the second heat dissipation pipe.
Japanese Unexamined Patent Application Publication (JP-A) No. 2005-4743 as conventional art 3 discloses an electronic device apparatus that can allow only cooling water to flow out without discharging air.
In this electronic device apparatus, a pipe on the side where cooling water flows out of a tank is disposed so as to extend to the central position of the tank and, further, two plates are provided in the tank so as to partition the neighborhood of a pipe inlet portion where the cooling water flows out. A cooling water injection jig having a tank joint portion is used for injecting the cooling water into the tank.
Japanese Unexamined Patent Application Publication (JP-A) No. 2005-166030 as conventional art 4 discloses a heat receiving unit in which a heat receiver having a cooling fluid path in a substrate composed of two aluminum high heat conductive plates, an expansion tank apparatus having a cooling fluid path, and a cooling fluid circulation path connecting both cooling fluid paths together are integrally provided and a cooling liquid is sealed in both cooling fluid paths and the cooling fluid circulation path, a method of manufacturing the receiving unit, and a heat dissipation apparatus.
In this liquid-cooling type heat dissipation apparatus, the expansion tank apparatus is provided with a tank placing base and an expansion tank provided on the tank placing base. The expansion tank comprises a tank body having a bulged portion and a bottom plate closing a lower end opening of the tank body and extending rearward further than the tank body. A baffle plate extending upward and inclined radially inward is integrally formed around the entire periphery of a through hole of the bottom plate so that an opening is formed surrounded by a tip end of the baffle plate.
The amount of the cooling liquid is set so that when the substrate is placed upside down, the cooling liquid fills the inside of the cooling fluid paths and the inside of the cooling fluid circulation path and further the liquid level of the cooling liquid in the bulged portion of the expansion tank is located above the opening at the tip end of the baffle plate at the bottom plate of the expansion tank.
Further, International Publication No. WO2005/002307 as conventional art 5 proposes a liquid-cooling apparatus completely sealed with a metal, which aims at minimizing liquid permeation in order to achieve a reduction in size and thickness.
This liquid-cooling apparatus is basically configured such that a plurality of metal plates formed with flow paths or the like in advance are joined together and is further configured such that a pump and a liquid storage tank are also integrally formed.
With the liquid-cooling type cooling system disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 2003-67087, there is a problem that the tube and so on are made of a resin material and thus the volume of a liquid storage tank for reserving in advance an amount corresponding to liquid permeation through the resin material increases, thus resulting in an increase in size of the entire system.
With the electronic device, the liquid-cooling system, and the liquid-cooling tank disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 2004-84958, there is a problem that since the flow paths are formed by the pipes, impact is given to the height of the device and thus a reduction in thickness cannot be achieved.
With the electronic device apparatus disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 2005-4743, there is a problem that since the two plates are provided in the tank so as to partition the neighborhood of the pipe inlet portion where the cooling water flows out and the cooling water injection jig having the tank joint portion is used for injecting the cooling water into the tank, impact is given to the height of the apparatus and thus a reduction in thickness cannot be achieved.
With the heat dissipation apparatus disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 2005-166030, there is a problem that since an upper-side storage space and a lower-side storage space are provided so as to sandwich an outflow end therebetween, the water storage tank can be provided only on the upper side with respect to the high heat conductive plate, so that height impact is given to the cooling system and thus a reduction in thickness cannot be achieved.
Further, with the heat dissipation apparatus disclosed in Japanese Unexamined Patent Application Publication (JP-A) No. 2005-166030, there is a problem that since the position of the opening formed by the baffle plate should be located at the center of the height of the tank or higher, the structure is largely restricted in height or the like.
Further, with the cooling apparatus disclosed in International Publication No. WO2005/002307, there is a problem that air is reserved in the liquid storage tank in advance for suppressing an increase in internal pressure due to a rise in temperature or an increase in internal pressure of the cooling apparatus due to generation of gas by corrosion reactions between a cooling liquid and a metal, but if the air enters the flow path during operation of the liquid-cooling apparatus, the cooling performance is lowered.
It is therefore an object of this invention to provide an electronic device cooling apparatus that can be mounted in a space.
It is another object of this invention to provide a liquid-cooling apparatus that can reduce height impact to an electronic device.
Further, it is another object of this invention to provide an electronic device cooling apparatus that can prevent a reduction in cooling performance and improve the reliability.